The present invention relates to the general field of turbine engines.
It relates more particularly to monitoring aviation turbine engines fitted with one or more rotary shafts, e.g. such as a turbojet or a turboprop.
In known manner, a rotary shaft of a turbojet, such as for example a low-pressure rotor, is subjected to a steady twisting force.
In addition, specific excitations may dynamically generate vibration in the rotary shaft at a particular frequency that is known as the twisting frequency of the shaft. This particular frequency characterizes the first twisting mode of the shaft. By way of example, for a low-pressure rotor of a turbojet, this frequency is low compared with the frequency of rotation of the rotor.
It can thus happen that pulsed injection of fuel into the turbojet enters into resonance with this first twisting mode of the turbojet shaft. Depending on the amplitude of this resonance, noise may be generated in the cabin, or there may be a risk of the shaft breaking as the result of vibration fatigue.
It is therefore necessary to monitor twisting vibration of the rotary shaft of a turbojet in order to avoid such drawbacks.